WEDNESDAY, Sept. 11 (HealthDay News) -- New research suggests that patients with obsessive-compulsive disorder do better when they combine intensive "exposure therapy" with an antidepressant rather than taking a common two-drug combination.

There are caveats, however: The kind of exposure therapy used in the study required patients to see therapists twice a week, which can be expensive; some obsessive-compulsive disorder (OCD) patients simply refuse to engage in this kind of therapy; and it's not clear what happens to patients in the long term.

Still, OCD patients who take antidepressants and still have symptoms should try exposure therapy before taking the medications with a drug known as risperidone, said study lead author Dr. Helen Blair Simpson, a professor of clinical psychiatry at Columbia University. "If risperidone is tried, clinicians should know that it is likely to help only a small subset, and it should be discontinued if there is no obvious benefit," she said.

About 1 percent of Americans suffer from OCD. Half of these people are thought to have severe cases, according to the U.S. National Institute of Mental Health.

People with OCD suffer from a variety of compulsions, rituals and obsessions, all of which can disrupt their lives and make them anxious. They may develop elaborate routines to avoid things like germs and become unable to stop their thoughts from racing over the same topic.

Psychiatrists often prescribe antidepressants known as selective serotonin reuptake inhibitors -- including Prozac, Paxil and others -- to people with OCD. But that's often not enough to help them.

That's where another drug, risperidone (brand name Risperdal), often is used. In some cases, psychiatrists prescribe it in addition to antidepressants because it's thought to help OCD patients. It's known as an antipsychotic drug, although it's used to treat a variety of mental illnesses.

Exposure therapy is a non-drug treatment designed to gradually help OCD sufferers overcome their fears by slowly exposing them to the things that scare them.

The new study aimed to find out if the drug combination works -- and also if it's better than antidepressants and exposure therapy.

Over five years, ending in 2012, researchers randomly assigned 100 adult OCD patients -- all of whom already were taking antidepressants -- to add risperidone or a placebo or take part in 17 twice-weekly sessions of exposure therapy. Fourteen patients dropped out, leaving 86 total.

After two months, 43 percent of patients who took an antidepressant plus exposure therapy had minimal symptoms of OCD, compared with 13 percent who added risperidone and 5 percent who took a placebo.

Side effects were more common among those who took risperidone.

"Some OCD patients won't do exposure therapy," Simpson said. "Some won't take medications, especially antipsychotic medications. For a study like this, patients had to be open to either treatments."

Paul Salkovskis, an OCD specialist and a professor of clinical psychology and applied science at the University of Bath, in England, praised the study and said the findings confirm that risperidone doesn't help OCD patients, while exposure and cognitive behavioral therapy "has a substantial effect."

"It's about as strong a study as can be -- properly conducted, properly reported and analyzed. It is world-changing for OCD patients," Salkovskis said. "People should be helped by their doctor to discontinue risperidone as soon as possible. The other implication is that there is an urgent need to make cognitive behavior therapy more available."